Re: [PATCH 1/4] mm/vmalloc: Remove unnecessary size ALIGN in __vmalloc_node_range_noprof

[Baoquan He <bhe@redhat.com>]

On 03/05/25 at 09:46am, liuye wrote:
> 
> 在 2025/3/4 02:30, Uladzislau Rezki 写道:
> > On Mon, Mar 03, 2025 at 05:44:07PM +0800, Liu Ye wrote:
> >> The same operation already exists in the function __get_vm_area_node,
> >> so delete the duplicate operation to simplify the code.
> >>
> >> Signed-off-by: Liu Ye <liuye@kylinos.cn>
> >> ---
> >>  mm/vmalloc.c | 1 -
> >>  1 file changed, 1 deletion(-)
> >>
> >> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> >> index dc658d4af181..20d9b9de84b1 100644
> >> --- a/mm/vmalloc.c
> >> +++ b/mm/vmalloc.c
> >> @@ -3798,7 +3798,6 @@ void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
> >>  			shift = arch_vmap_pte_supported_shift(size);
> >>  
> >>  		align = max(real_align, 1UL << shift);
> >> -		size = ALIGN(real_size, 1UL << shift);
> >>  	}
> >>  
> >>  again:
> >> -- 
> >> 2.25.1
> >>
> > There is a mess with:
> >
> >  unsigned long real_size = size;
> >  unsigned long real_align = align;
> >
> > "real_size" and "real_align". Those are useless. What is about:
> 
> Sorry, the order of the patches may be misleading.
> 
> The correct order is as follows：
> 
> PATCH1.  mm/vmalloc: Size should be used instead of real_size "
> PATCH2.  mm/vmalloc: Remove unnecessary size ALIGN in __vmalloc_node_range_noprof                 
> PATCH3.  mm/vmalloc: Remove the real_size variable to simplify the code "
> PATCH4.  mm/vmalloc: Rename the variable real_align to original_align to prevent misunderstanding
> 
> If PATCH1 is the correct fix, then consider PATCH2, PATCH3, and PATCH4.

Well, seems the patch split is done too subtly. It's only about the
size/align inside one function, maybe one patch is enough in this case.
My personal opinion.

> 
> > diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> > index 5c88d0e90c20..a381ffee1595 100644
> > --- a/mm/vmalloc.c
> > +++ b/mm/vmalloc.c
> > @@ -3771,8 +3771,6 @@ void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
> >  	struct vm_struct *area;
> >  	void *ret;
> >  	kasan_vmalloc_flags_t kasan_flags = KASAN_VMALLOC_NONE;
> > -	unsigned long real_size = size;
> > -	unsigned long real_align = align;
> >  	unsigned int shift = PAGE_SHIFT;
> >  
> >  	if (WARN_ON_ONCE(!size))
> > @@ -3781,7 +3779,7 @@ void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
> >  	if ((size >> PAGE_SHIFT) > totalram_pages()) {
> >  		warn_alloc(gfp_mask, NULL,
> >  			"vmalloc error: size %lu, exceeds total pages",
> > -			real_size);
> > +			size);
> >  		return NULL;
> >  	}
> >  
> > @@ -3798,19 +3796,18 @@ void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
> >  		else
> >  			shift = arch_vmap_pte_supported_shift(size);
> >  
> > -		align = max(real_align, 1UL << shift);
> > -		size = ALIGN(real_size, 1UL << shift);
> > +		align = max(align, 1UL << shift);
> >  	}
> >  
> >  again:
> > -	area = __get_vm_area_node(real_size, align, shift, VM_ALLOC |
> > +	area = __get_vm_area_node(size, align, shift, VM_ALLOC |
> >  				  VM_UNINITIALIZED | vm_flags, start, end, node,
> >  				  gfp_mask, caller);
> >  	if (!area) {
> >  		bool nofail = gfp_mask & __GFP_NOFAIL;
> >  		warn_alloc(gfp_mask, NULL,
> >  			"vmalloc error: size %lu, vm_struct allocation failed%s",
> > -			real_size, (nofail) ? ". Retrying." : "");
> > +			size, (nofail) ? ". Retrying." : "");
> >  		if (nofail) {
> >  			schedule_timeout_uninterruptible(1);
> >  			goto again;
> > @@ -3860,7 +3857,7 @@ void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
> >  	    (gfp_mask & __GFP_SKIP_ZERO))
> >  		kasan_flags |= KASAN_VMALLOC_INIT;
> >  	/* KASAN_VMALLOC_PROT_NORMAL already set if required. */
> > -	area->addr = kasan_unpoison_vmalloc(area->addr, real_size, kasan_flags);
> > +	area->addr = kasan_unpoison_vmalloc(area->addr, size, kasan_flags);
> >  
> >  	/*
> >  	 * In this function, newly allocated vm_struct has VM_UNINITIALIZED
> > @@ -3878,8 +3875,6 @@ void *__vmalloc_node_range_noprof(unsigned long size, unsigned long align,
> >  fail:
> >  	if (shift > PAGE_SHIFT) {
> >  		shift = PAGE_SHIFT;
> > -		align = real_align;
> > -		size = real_size;
> >  		goto again;
> >  	}
> >  
> > ?
> >
> > --
> > Uladzislau Rezki
>